The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Recently, a rise in oil prices has caused manufacturers all over the world to rush into infinite competition. For engines in particular, manufacturers have been trying to reduce the weight and improve fuel efficiency through downsizing and similar measures.
Alternatively, as a method capable of improving fuel efficiency through the transmission in a vehicle, there is a method of operating an engine at a more efficient operation point by increasing the shifting stages of the transmission, thereby improving fuel efficiency.
Increasing the shifting stages of the transmission enables an engine to operate in a relatively lower range of RPM, so a vehicle can run more quietly.
However, as the shifting stages of a transmission increase, the number of parts in the transmission increases, so the manufacturing cost, weight, and power transmission efficiency may become poor.